This invention relates to semiconductor processing, and, in particular, to methods and apparatus for curing a layer of a processable material on a substrate.
Curing of processable materials is a common practice in photolithography. In material processing methodologies (such as photolithography), creating patterned layers involves the application of a thin layer of radiation-sensitive material, such as photoresist, to an upper surface of a substrate. This radiation-sensitive material is transformed into a patterned mask that can be used to etch or transfer a pattern into an underlying layer on a substrate. Patterning of the radiation-sensitive material generally involves exposure by a radiation source through a reticle (and associated optics) onto the radiation-sensitive material using, for example, a photolithography system. This exposure can then be followed by the removal of irradiated regions of the radiation-sensitive material (as in the case of positive photoresist), or non-irradiated regions (as in the case of negative resist) using a developing solvent.
Using resist coatings typically includes baking. The baking (curing) of organic films is critical to the manufacturing process used for integrated circuits. This process is typically referred to as a “post apply bake” or PAB. Typical films include top coat barrier layers (TC), top coat antireflective layers (TARO), bottom antireflective layers (BARO), imaging layers (PR or photoresist), and sacrificial and barrier layers (hard mask) for etch stopping. Curing of films also typically includes a post exposure bake (PEB). The bake process time and temperature are used to drive out solvents and cure or harden the film and thereby define the characteristics of the film at exposure and post exposure develop where circuit features are defined, prior to etching the features into the substrate. Thermal processing of such films enables subsequent use and processing of the patterned photoresist.